1. Field of the Invention
The present invention generally relates to a control method, and a control apparatus used in a communication apparatus that communicates with portable electronic data communication appliances, and also a storage medium for storing a control program of such a control apparatus. More specifically, the present invention is directed to such a control apparatus arranged by an apparatus main body, and a connection apparatus capable of providing an additional function, while connecting a separate module to an electronic data communication appliance. Also, the present invention is directed to a control method for realizing such an additional function, and further to a storage medium for storing a control program used to realize such an additional function.
2. Description of the Prior Art
Very recently, various sorts of communication services have been proposed while using public lines. These communication services are realized by connecting, for example, a communication modem functioning as an external expansion unit to a personal computer so as to establish a connection between this personal computer and an external line.
Similar to the personal computer, even in a portable electronic information apparatus typically known as a PDA (personal Digital Assistants), a main body of this PDA is connected via a communication modem (external expansion unit) separately connectable with this PDA to a public line, so that various sorts of communication services are accessible.
Since the protocol for these various sorts of communication services differs from each other, depending upon these sorts, different sorts of communication software (programs) are required. The communication software is needed to execute auto-log-in operations. In the auto-log-in operation, complex sequential operations are automatically processed in which data transmission/reception are controlled, the transmitted/received data are displayed, files are transferred, and desirable communication services are received.
Therefore, in the conventional PDA, several sorts of communication programs suitable to several sorts of communication services have been previously installed in a ROM built in a main body of this PDA. A communication modem functioning as an external expansion unit is mounted on this PDA so as to select a desirable communication service, so that the communication program corresponding to this desirable communication program is initiated to control a CPU provided in this main body, and also a circuit operation of the communication modem.